The Avian Flu: Are Americans at Risk?

Tuesday, August 12 2008

In recent years, the avian flu, or bird flu, has gained widespread attention as the next possible worldwide pandemic (worldwide outbreak of disease). Avian influenza is an infection caused by viruses that occur naturally among birds. Wild birds worldwide carry the viruses, but usually do not get sick from them. However, avian flu is very contagious among birds, and can be fatal among domesticated poultry, including chickens, ducks, and turkeys.

Human Cases of Bird Flu

The H5N1 virus is an influenza A virus subtype occurring mainly in birds. This potentially-deadly virus is highly contagious among birds. H5N1 virus does not normally infect people, but infections can, and have, occurred in humans, increasingly so in recent years. Most of these cases have been the result of people having direct or close contact with either H5N1-infected poultry or H5N1-contaminated surfaces.

Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of detected cases of severe disease and death in people. However, it is possible that the most severe people are more likely to be diagnosed and reported, while milder cases are not.

Where Bird Flu Is Happening

According to the World Health Organization (WHO), from 2003 through January 2008, more than 200 reported deaths worldwide have occurred from the bird flu. Some countries reporting deaths from the HN51 virus have included:

• Azerbaijan – 5 deaths
• Cambodia – 7 deaths
• China – 17 deaths
• Egypt – 19 deaths
• Indonesia – 98 deaths
• Iraq – 2 deaths
• Lao People's Democratic Republic – 2 deaths
• Nigeria – 1 death
• Pakistan – 1 death
• Thailand – 17 deaths
• Turkey – 4 deaths
• Viet Nam – 4 deaths

There may have been other deaths that the WHO is not aware of. In addition, many hundreds of people have been sickened by the bird flu, and perhaps many more have been sick or died because of it but have been undiagnosed or misdiagnosed.

Disease Is Rare

In general, H5N1 remains a very, very rare disease in humans when compared to the world’s population of more than 6 billion people. The virus doesn’t infect humans easily, and if a person is infected, it is very difficult for the virus to spread to another person.

While there has been some documented human-to-human spread of the bird flu virus, it has been limited and unsustained. For example, it is believed that in Thailand in 2004, probable person-to-person spread of the virus, resulting from prolonged and very close contact between a sick child and her mother, occurred.

In June 2006, the WHO reported evidence of human-to-human spread in Indonesia, which has reported more bird flu deaths than any other nation to this point. In this situation, 8 people in one family were infected. The first family member to become ill was thought to have contracted the avian flu through contact with infected poultry. It is believed this person then infected 6 family members, and one of those 6 people then infected another family member. No further spread of the virus beyond the exposed family was suspected or documented. 

Virus Could Change and Spread

Nevertheless, all influenza viruses have the ability to change, and scientists are concerned that the H5N1 virus could one day have the capability to infect humans, and could become contagious enough to spread easily from one person to another. People have little or no natural immunity to H5N1. If the H5N1 virus changed to the degree that it had the capacity to spread easily from human to human, an influenza pandemic could occur. And in this world where people routinely travel the world and carry disease from one continent to another, that pandemic could be the greatest outbreak of disease in human history.

Obviously, no one can predict when such an event might occur. Experts are watching the H5N1 situation in Asia and Europe, and are preparing for the possibility that the virus could begin to spread from person to person.

Treatment and Vaccination for the H5N1 Virus in People

The H5N1 virus that has caused people to become ill and die in Asia is resistant to two antiviral medications commonly used for influenza, rimantadine and amantadine. Zanamivir and oseltamivir, two other antiviral medications, may work to treat the bird flu, but more studies still need to be done to determine how successful they would be.

How Bird Flu Manifests Itself

People infected with the H5N1 virus exhibit classic flu-like symptoms, such as:

• Fever greater than 100.4°F (38°C)
• Headache
• Diarrhea
• Cough (either dry or productive)
• Sore throat
• Difficulty breathing
• Runny nose
• Muscle aches
• General malaise

No Real Threat Seen – For Now

Again, when compared to the number of people on this planet, and the other challenges that face us, both natural and man-made, the avian flu isn’t much of a threat to Americans or anyone else. But as quickly as things change in this world, it may become a threat tomorrow. To prepare for that possibility, some of the world’s finest scientific minds are taking the H5N1 virus, and the consequences of its proliferation, very seriously.